Pesticide drift impacting millions of acres

Recent studies show over 3.1 million acres of soybeans have been damaged by dicamba drift this year. (MGN Online)

KIRKSVILLE, Mo —

An early September report out of the University of Missouri shows that nationwide 2,242 farmers have stated that dicamba has damaged an estimated 3.1 million acres this year.

In Iowa, ag leaders are investigating a record number of crop damage reports of pesticide misuse. 100 out of the 258 reports, through September, deal directly with dicamba damage and it’s impact on roughly 150,000 acres in Iowa.

This major issue forced the Missouri Department of Agriculture to ban the sale and use of dicamba products in Missouri back on July 7th. While many reports to get acknowledged and recorded by both Missouri and Iowa Ag agencies, MU weed scientist Kevin Bradley says “for every case reported there are probably ten more not reported.”

Speaking to a MU field day in August Bradely said off target dicamba damage can be blamed on several causes, including volatility, illegal use and poor sprayers, they physical drift of the product, or more recently the spraying of dicamba during temperature inversions.

A temperature inversion is defined as a reversal of the normal behavior of temperature near the surface, in which a layer of cool air at the surface is overlain by a layer of warmer air.

Back in 2014 Bradley began working with Missouri state climatologist Dr. Patrick Guinan and his Missouri Mesonet, a collection of 35 weather stations in 24 counties across Missouri. The Mesonet weather stations currently measure seven standard weather variables – air temperature, humidity, wind speed, wind direction, soil temperatures at 2 inch and 4 inch depths, rainfall and solar radiation. To detect temperature inversions Bradley and Guinan added two more temperature monitors at 10 feet off the ground and 1.5 feet off the gound.

“The purpose was to monitor for inversions and the impact that may have on pesticides particularly dicamba since it’s highly volatile and it’s not recommended to be sprayed during inversions,” said Guinan.

In 2015 Guinan and Bradley added the extra temperature instruments to 3 different stations in the Mesonet. Using the data collected from both heights a temperature profile can be created allowing researchers to monitor for inversions.

“The research of the data coming in by an associate, a scientist, Mandy Bish who’s done a lot of work on this data indicates that these inversions are very common,” Pat said. This year they added six more sites of the Mesonet to their temperature inversion study, increasing the total number of stations to nine across the state.

It wasn’t much longer until the data started to show a trend in the inversions. “Typically the inversions set up just prior to sunset, the winds start to die down, the sun goes down and you start to set up an inversion,” Guinan said. According to the data once the inversions set up they typically last through the night and they start to mix out as the sun comes up the next morning.

While ag giants Monsanto, DuPont and BASF have genetically modified seeds that are dicamba resistant that doesn’t solve the problem of off-target damage from the dicamba drift onto neighboring fields. Currently most Ag companies are saying that their product is in line with EPA standards and their labels state that if the directions are followed there will be no off-target movement of dicamba due to wind or volatization.

Many of the country’s weed scientists including Bradley and Bish disagree saying that instances of volatization still occur. The EPA is currently looking into new restrictions on dicamba based on the data and research being conducted this year.

One of the worst states affected is Arkansas, where 963 dicamba related complaints had been logged by July. Monsanto’s VP of global strategy, Scott Partridge, had stated earlier this year that better education will reduce damage while siting Georgia as the best example where new certifications are required leading to no reports of drift damage this year. Iowa State University weed scientist Bob Hartzler believes damage from dicamba can range from zero impact up to a 40% yield reduction just based on Iowa reports.

The question now remains, who will have to pay if insurance companies won’t? MU Ag economist Ray Massey says “sometimes neighbors can work out damage issues with each other, particularly small cases, beyond that, many neighbors may not take responsibility and in those cases farmers may have to file a civil lawsuit and should think about contacting an attorney.”